1. Field of the Invention
The present invention is directed to toilet flushing. It finds particular, although not exclusive, application in tank-type flushers.
2. Background Information
Toilet flushers come in a wide arrange of designs. (We use the term toilet here in its broad sense, which encompasses what are variously referred to as toilets, water closets, urinals, etc.) Many designs are of the gravity type, which uses the pressure that results from the weight of water stored in a tank to flush the bowl and provide the siphoning action by which the bowl's contents are drawn from it. Any flusher of this type employs a main flush valve, which controls the release of water from the tank through the tank outlet that leads to the bowl. For the flusher to act effectively, that flush valve must remain open long enough to let the required amount of water flow from it into the bowl.
If A popular way of achieving the proper flush-valve-opening duration is to employ a pivoting flush valve on which a timer cup is disposed. The valve is pivoted to unseat it, and water in the full flush tank fills the timer cup. This so weights the cup that it keeps the valve pivoted to the open position. An orifice in the timer cup allows water to leak from it when the tank level has fallen below that of the timer cup. After a length of time great enough to allow most of the liquid to drain from the timer cup, the flush valve then pivots back into its closed position.
Another popular approach, typically used in automatic toilets, is to use a timer circuit to time activation of a solenoid that controls the flush valve's operation. An advantage of many such installations is that they use line pressure to operate the flush valve and can therefore be arranged so that the flush valve seals more effectively than the typical manual flusher's.